The Norwegian Adult Mental Health Registry for Quality Control in Specialized Mental Health Services: Protocol for a Nationwide Naturalistic Study.

Background: Mental disorders are highly prevalent, and they significantly impact individuals and society. Patients experiencing long-term, severe mental disorders with functional impairment and reduced quality of life often have a history of adolescent onset anxiety and depressive disorders. Despite the long-term costs to both patients and society, studies examining treatment effects over time and across diagnoses are scarce. Objective: The Norwegian Adult Mental Health Registry (NAMHR) aims to systematically reuse health data to monitor and improve treatment outcomes, patient safety, health service quality, and research. The registry addresses the need for comprehensive data on the effects and utility of mental health services, interventions, and therapy variants in specialized mental health care. Methods: The NAMHR is a nationwide naturalistic registry, including all Norwegian adults eligible for treatment in specialized mental health care services who have not opted out. Patients are automatically enrolled when treated in these services. The population includes patients treated in public specialized services and those treated in private services having a contract with public health services. The registry is based on secondary data from the Norwegian Patient Registry (NPR), patient-reported outcome measures (PROMs), patient-reported experience measures (PREMs), the Norwegian Registry for Primary Health Care (KPR), and several other sources, including electronic health records (EHRs). Data linkage uses unique national identity numbers, ensuring high-quality data. The registry collects information on diagnoses, treatments, medication, and patient-reported outcomes, providing a holistic approach to mental health care. Statistical analyses will be defined in each project. Results: As of December 2025, the NAMHR is approved and is being constructed. The registry anticipates enrolling up to 170,000 participants, with a new incidence rate of around 10,000 patients per year. Key predictors and outcomes include PROMs and PREMs, and automatically reported measures involving a wide range of data, including EHR data from inpatient and outpatient treatments, data from primary health care, data on job and education status, and data on cause of death. Enrollment is planned to start in 2026, initially by adding journal data and patient-reported data. Other sources will be included. The NAMHR has no planned end date. Results will be made available for internal quality improvement purposes, and data for research are expected to be available around mid-2026 for approved projects. Conclusions: The NAMHR will promote quality improvement initiatives and research, including registry-based randomized clinical trials. It will also be possible to link the NAMHR to a similar registry for children and adolescents, making it possible to follow patients from birth to death and supporting the monitoring of diagnostic drift. The NAMHR will inform health policy decisions at local, regional, national, and international levels, contributing to the evaluation and development of clinical guidelines and enhancing personalized treatment approaches.